Methods and devices for measuring fundamental data of lenses

Abstract

A measurement device may illuminate lens 10 to be inspected with light at a plurality of different angles of incidence. The transmitted light that passes through lens 10 may be preferably detected by light detecting means 36 . When light detecting means 36 detects the light, it outputs an electrical signal. Control unit 54 may (1) align light source 22 in the predetermined position and turns it on and (2) calculate the degree of refraction of the transmitted light that passes through lens 10 , based upon the electrical signal output from light detecting means 36 . Then, control unit 54 may further (3) conduct illumination at a plurality of different angles of incidence and obtain a plurality of “angle of incidence—degree of refraction” relationships from the degree of refraction calculated for each angle of incidence, and (4) calculate the fundamental data of lens 10 by using the plurality of “angle of incidence—degree of refraction” relationships.

1. A method for measuring fundamental data of a lens, comprising the steps of:
 illuminating a first measurement point of the lens with a first light at a first predetermined angle of incidence from a first surface side of the lens, 
 measuring a first degree of refraction of the first transmitted light that passes through the lens from a second surface side of the lens; 
 illuminating the first measurement point with a second light at a second predetermined angle of incidence from the first surface side of the lens; 
 measuring a second degree of refraction of the second transmitted light that passes through the lens from the second surface side of the lens; 
 illuminating the first measurement point with a third light at a third predetermined angle of incidence from the first surface side of the lens; 
 measuring a third degree of refraction of the third transmitted light that passes through the lens from the second surface side of the lens; 
 illuminating a second measurement point with a fourth light at a fourth predetermined angle of incidence from the second surface side of the lens; 
 measuring a fourth degree of refraction of the fourth transmitted light that passes through the lens from the first surface side of the lens; 
 illuminating the second measurement point with a fifth light at a fifth predetermined angle of incidence from the second surface side of the lens; 
 measuring a fifth degree of refraction of the fifth transmitted light that passes through the lens from the first surface side of the lens; 
 illuminating the second measurement point with a sixth light at a sixth predetermined angle of incidence from the second surface side of the lens; 
 measuring a sixth degree of refraction of the sixth transmitted light that passes through the lens from the first surface side of the lens; 
 calculating a thickness of the lens, a focal distance of the first side surface of the lens, a focal distance of the second side surface of the lens, a focal distance of the lens, a curvature of radius of the first side surface of the lens, a curvature of radius of the second side surface of the lens and a refractive index of the lens based upon first, second, third, fourth, fifth and sixth “angle of incidence—degree of refraction” relationships; and 
 outputting at least one of the calculated thickness of the lens, focal distance of the first side surface of the lens, focal distance of the second side surface of the lens, focal distance of the lens, curvature of radius of the first side surface, curvature of radius of the second side surface, and a refractive index of the lens. 
 
   
   
     2. A method for measuring fundamental data of a lens, comprising the steps of:
 illuminating the lens with a light at a predetermined angle of incidence from a first surface side of the lens, 
 measuring degree of refraction of the transmitted light that passes through the lens from a second surface side of the lens; 
 measuring a thickness of the lens; 
 calculating the fundamental data of the lens based upon a plurality of “angle of incidence—degree of refraction” relationships obtained by measuring the degree of refraction with respect to at least two different angles of incidence obtained for each of the two surfaces of the lens and the thickness of the lens; and 
 outputting the calculated fundamental data of the lens. 
 
   
   
     3. A method for measuring fundamental data of a lens, comprising the steps of:
 illuminating the lens with a light at a predetermined angle of incidence from a first surface side of the lens, 
 measuring degree of refraction of the transmitted light that passes through the lens from a second surface side of the lens; 
 calculating the fundamental data of the lens based upon a plurality of “angle of incidence —degree of refraction” relationships obtained by measuring the degree of refraction with respect to a plurality of different angles of incidence; and 
 outputting the calculated fundamental data of the lens; 
 wherein the calculating step comprises the steps of (1) representing the fundamental data of the lens as a function having a refractive index as a variable, based upon the “angle of incidence—degree of refraction” relationships relating to at least three different angles of incidence obtained for one surface of the lens, and (2) calculating the changes in the fundamental data at each measurement point by substituting appropriate numerical values for the refractive index. 
 
   
   
     4. A device for measuring the fundamental data of a lens, comprising:
 means for illuminating a measurement point of the lens with light at a plurality of different angles of incidence from a first surface side of the lens; 
 means for detecting transmitted light that passes through the lens from a second surface side of the lens; and 
 a processor in communication with the illuminating means and the detecting means, the detecting means communicating signals corresponding to the transmitted light to the processor, wherein the processor (1) causes illumination of the measurement point with the light from the illuminating means at the plurality of different angles of incidence, respectively, (2) calculates the respective degree of refraction of the transmitted light that passes through the lens based upon the output signal of the detecting means, and (3) calculates the fundamental data of the lens based upon a plurality of “angle of incidence—degree of refraction” relationships obtained for the plurality of different angles of incidence at the measurement point. 
 
   
   
     5. A measurement device as in  claim 4 , further comprising means for displaying the fundamental data calculated by the processor. 
   
   
     6. A measurement device as in  claim 5 , wherein the displaying means displays a graph showing the relationship between the movement of measurement points occurring when the measurement points are moved in the predetermined direction on the surface of the lens and the respective changes in the fundamental data. 
   
   
     7. A device for measuring the fundamental data of a lens, comprising:
 means for illuminating the lens with light at a plurality of different angles of incidence; 
 means for detecting transmitted light that passes through the lens; and 
 a processor in communication with the illuminating means and the detecting means, the detecting means communicating signals corresponding to the transmitted light to the processor, wherein the processor (1) causes illumination of the lens with the light from the illuminating means at the predetermined angle of incidence, (2) calculates the degree of refraction of the transmitted light that passes through the lens based upon the output signal of the detecting means, and (3) calculates the fundamental data of the lens based upon a plurality of “angle of incidence—degree of refraction” relationships obtained for a plurality of different angles of incidence; 
 wherein the illuminating means comprises a light source and a means for changing the optical distance between the light source and the lens. 
 
   
   
     8. A measurement device as in  claim 7 , wherein the changing means moves the light source in the axial direction, thereby changing the optical distance between the light source and the lens. 
   
   
     9. A measurement device as in  claim 7 , wherein the illuminating means further comprises a condensing lens disposed between the light source and the lens, wherein the changing means changes the position of the condensing lens in the axial direction, thereby changing the optical distance between the light source and the lens. 
   
   
     10. A measurement device as in  claim 7 , wherein the illuminating means further comprises a plurality of condensing lenses with different refractive powers, wherein the changing means selectively disposes any of the plurality of condensing lenses between the light source and the lens, thereby changing the optical distance between the light source and the lens. 
   
   
     11. A measurement device as in  claim 4 , wherein the illuminating means comprises a plurality of light sources disposed in a plurality of respective positions with different distances from the lens, and a reflective mirror for illuminating the lens with light from any of those light sources. 
   
   
     12. A measurement device as in  claim 4 , wherein the illuminating means illuminates the lens at no less than two of the three different types of illumination angles: divergent light, parallel light, and condensing light.